The present invention relates to vehicle suspensions in general, and more particularly to an arrangement for regulating the level and inclination of a vehicle.
There are already known various constructions of level and inclination regulating arrangements for vehicles. An arrangement of this type usually includes at least two pneumatic or hydropneumatic resilient elements each of which is associated with a different wheel of an axle or a side of the vehicle. The resilient elements include a movable separating piston which is loaded on its one side by the wheel load and on its other side by a supporting pressure of a gas cushion which is confined in a housing and supports the separating piston.
Resilient elements of this type render it possible to achieve level and inclination regulation of the vehicle by adjusting the oil quantity or the gas amount to a static change in the wheel load during the loading and unloading of the vehicle, and to a quasi-static change render the wheel loading in driving conditions which are influenced by mass forces during the negotiation of curves or during breaking or acceleration.
In a known hydraulic-pneumatic resilient arrangement of this type, which is disclosed in the published German patent application No. DE-AS 11 22 286, a level and an inclination regulation for a four-wheel vehicle is achieved by using three level regulating devices arranged between the wheels and the superstructure. Such regulating arrangements influence the oil quantity by adding oil to or removing oil from the oil quantity. The resilient arrangement further includes four filling regulators each of which is connected with a separating piston and which are operative for displacing the separating pistons back toward a central position by adding or removing gas. Both the oil quantity and the gas amount are variable and, therefore, the expense incurred in constructing the position regulating arrangement of this type is disadvantageously high.
There is also known, from the published German patent application No. DE-OS 34 27 902, a regulating arrangement of the above-mentioned type with a fitting adjustment of the gas amount, in which position regulating elements are provided which are respectively associated with the individual ones of the resilient elements and which detect the position of a separating piston with respect to a desired position and, when a deviation from such a desired position is encountered and detected, cause gas to be discharged from the resilient element through a discharge conduit into a low-pressure accumulator, or cause gas to be supplied to the respective resilient element through a supply conduit from a high-pressure accumulator which is being charged with relatively high pressurized gas by a compressor which withdraws the gas from the low-pressure accumulator.
In addition thereto, there are provided, for a resilient group including two resilient elements which provide a supporting moment in driving conditions that are influenced by mass forces, respective devices which effect direct gas flow from the gas cushion of that one of the resilient elements which is extended into the gas cushion of the other resilient element which is retracted, wherein the connections of the discharge conduits to the low-pressure accumulator and of the supply conduits to the high-pressure accumulator are closeable. A multitude of auxiliary means in the form of two gas accumulators, two compressors and a plurality of regulating elements in the discharge and supply conduits are required in this construction, in a very expensive manner, for the achievement of the level of inclination regulation.